Top port multi-part surface mount silicon condenser microphone

ABSTRACT

The present invention relates to a surface mount package for a micro-electro-mechanical system (MEMS) microphone die and methods for manufacturing the surface mount package. The surface mount package uses a limited number of components that simplifies manufacturing and lowers costs. The surface mount package features a substrate that performs functions for which multiple components were traditionally required, including providing an interior surface on which the MEMS microphone die is mechanically attached, providing an interior surface for making electrical connections between the MEMS microphone die and the package, and providing an exterior surface for surface mounting the microphone package to a device&#39;s printed circuit board and for making electrical connections between the microphone package and the device&#39;s circuit board. The microphone package has a substrate with metal pads on its top and bottom surfaces, a sidewall spacer, and a lid. A MEMS microphone die is mounted on the substrate, and the substrate, the sidewall spacer, and the lid are joined together to form the MEMS microphone.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/732,265 (now U.S. Pat. No. 8,629,552), filed Dec. 31, 2012, which isa continuation of U.S. patent application Ser. No. 13/286,558 (now U.S.Pat. No. 8,358,004), filed Nov. 1, 2011, which is a continuation of U.S.patent application Ser. No. 13/111,537 (now U.S. Pat. No. 8,121,331),filed May 19, 2011, which is a continuation of U.S. patent applicationSer. No. 11/741,881 (now U.S. Pat. No. 8,018,049), filed Apr. 30, 2007,which is a divisional of U.S. patent application Ser. No. 10/921,747(now U.S. Pat. No. 7,434,305), filed Aug. 19, 2004, which is acontinuation-in-part of U.S. patent application Ser. No. 09/886,854 (nowU.S. Pat. No. 7,166,910), filed Jun. 21, 2001, which claims the benefitof U.S. Provisional Patent Application No. 60/253,543, filed Nov. 28,2000. U.S. patent application Ser. No. 13/668,035, filed Nov. 2, 2012,U.S. patent application Ser. No. 13/668,103, filed Nov. 2, 2012, U.S.patent application Ser. No. 13/732,120, filed Dec. 31, 2012, U.S. patentapplication Ser. No. 13/732,179, filed Dec. 31, 2012, U.S. patentapplication Ser. No. 13/732,205, filed Dec. 31, 2012, and U.S. patentapplication Ser. No. 13/732,232, filed Dec. 31, 2012, are alsocontinuations of U.S. patent application Ser. No. 13/286,558 (now U.S.Pat. No. 8,358,004). These applications are hereby incorporated byreference herein in their entireties for all purposes.

TECHNICAL FIELD

This patent relates generally to a housing for a transducer. Moreparticularly, this patent relates to a silicon condenser microphoneincluding a housing for shielding a transducer.

BACKGROUND OF THE INVENTION

There have been a number of disclosures related to building microphoneelements on the surface of a silicon die. Certain of these disclosureshave come in connection with the hearing aid field for the purpose ofreducing the size of the hearing aid unit. While these disclosures havereduced the size of the hearing aid, they have not disclosed how toprotect the transducer from outside interferences. For instance,transducers of this type are fragile and susceptible to physical damage.Furthermore, they must be protected from light and electromagneticinterferences. Moreover, they require an acoustic pressure reference tofunction properly. For these reasons, the silicon die must be shielded.

Some shielding practices have been used to house these devices. Forinstance, insulated metal cans or discs have been provided.Additionally, DIPs and small outline integrated circuit (SOIC) packageshave been utilized. However, the drawbacks associated with manufacturingthese housings, such as lead time, cost, and tooling, make these optionsundesirable.

SUMMARY OF THE INVENTION

The present invention is directed to a silicon condenser microphonepackage that allows acoustic energy to contact a transducer disposedwithin a housing. The housing provides the necessary pressure referencewhile at the same time protects the transducer from light,electromagnetic interference, and physical damage. In accordance with anembodiment of the invention a silicon condenser microphone includes atransducer and a substrate and a cover forming the housing. Thesubstrate may have an upper surface with a recess formed thereinallowing the transducer to be attached to the upper surface and tooverlap at least a portion of the recess thus forming a back volume. Thecover is placed over the transducer and includes an aperture adapted forallowing sound waves to reach the transducer.

Other features and advantages of the invention will be apparent from thefollowing specification taken in conjunction with the followingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a first embodiment of a siliconcondenser microphone of the present invention;

FIG. 2 is a cross-sectional view of a second embodiment of a siliconcondenser microphone of the present invention;

FIG. 3 is a cross-sectional view of a third embodiment of a siliconcondenser microphone of the present invention;

FIG. 4 is a cross-sectional view of the third embodiment of the presentinvention affixed to an end user circuit board;

FIG. 5 is a cross-sectional view of the third embodiment of the presentinvention affixed to an end user circuit board in an alternate fashion;

FIG. 6 is a plan view of a substrate to which a silicon condensermicrophone is fixed;

FIG. 7 is a longitudinal cross-sectional view of a microphone package ofthe present invention;

FIG. 8 is a lateral cross-sectional view of a microphone package of thepresent invention;

FIG. 9 is a longitudinal cross-sectional view of a microphone package ofthe present invention;

FIG. 10 is a lateral cross-sectional view of a microphone package of thepresent invention;

FIG. 11 is a cross-sectional view of a top portion for a microphonepackage of the present invention;

FIG. 12 is a cross-sectional view of a top portion for a microphonepackage of the present invention;

FIG. 13 is a cross-sectional view of a top portion for a microphonepackage of the present invention;

FIG. 14 a is a cross-sectional view of a laminated bottom portion of ahousing for a microphone package of the present invention;

FIG. 14 b is a plan view of a layer of the laminated bottom portion ofFIG. 14 a;

FIG. 14 c is a plan view of a layer of the laminated bottom portion ofFIG. 14 a;

FIG. 14 d is a plan view of a layer of the laminated bottom portion ofFIG. 14 a;

FIG. 15 is a cross-sectional view of a bottom portion for a microphonepackage of the present invention;

FIG. 16 is a cross-sectional view of a bottom portion for a microphonepackage of the present invention;

FIG. 17 is a cross-sectional view of a bottom portion for a microphonepackage of the present invention;

FIG. 18 is a cross-sectional view of a bottom portion for a microphonepackage of the present invention;

FIG. 19 is a plan view of a side portion for a microphone package of thepresent invention;

FIG. 20 is a cross-sectional view of a side portion for a microphonepackage of the present invention;

FIG. 21 is a cross-sectional view of a side portion for a microphonepackage of the present invention;

FIG. 22 is a cross-sectional view of a side portion for a microphonepackage of the present invention;

FIG. 23 is a cross-sectional view of a microphone package of the presentinvention;

FIG. 24 is a cross-sectional view of a microphone package of the presentinvention;

FIG. 25 is a cross-sectional view of a microphone package of the presentinvention;

FIG. 26 is a cross-sectional view of a microphone package of the presentinvention;

FIG. 27 is a cross-sectional view of a microphone package of the presentinvention with a retaining ring;

FIG. 28 is a cross-sectional view of a microphone package of the presentinvention with a retaining wing;

FIG. 29 is a cross-sectional view of a microphone package of the presentinvention with a retaining ring;

FIG. 30 is a plan view of a panel of a plurality of microphone packages;and

FIG. 31 is a plan view of a microphone pair.

DETAILED DESCRIPTION

While the invention is susceptible of embodiments in many differentforms, there is shown in the drawings and will herein be described indetail several possible embodiments of the invention with theunderstanding that the present disclosure is to be considered as anexemplification of the principles of the invention and is not intendedto limit the broad aspect of the invention to the embodimentsillustrated.

The present invention is directed to microphone packages. The benefitsof the microphone packages disclosed herein over microphone packagingutilizing plastic body/lead frames include the ability to processpackages in panel form allowing more units to be formed per operationand at much lower cost. The typical lead frame for a similarlyfunctioning package would contain between 40 and 100 devices connectedtogether. The present disclosure would have approximately 14,000 devicesconnected together (as a panel). Also, the embodiments disclosed hereinrequire minimal “hard-tooling” This allows the process to adjust tocustom layout requirements without having to redesign mold, lead frame,and trim/form tooling.

Moreover, many of the described embodiments have a better match ofthermal coefficients of expansion with the end user's PCB, typicallymade of FR-4, since the microphone package is also made primarily ofFR-4. These embodiments of the invention may also eliminate the need forwire bonding that is required in plastic body/lead frame packages. Thefootprint is typically smaller than that would be required for a plasticbody/lead frame design since the leads may be formed by plating athrough-hole in a circuit board to form the pathway to the solder pad.In a typical plastic body/lead frame design, a (gull wing configurationwould be used in which the leads widen the overall foot print.

Now, referring to FIGS. 1-3, three embodiments of a silicon condensermicrophone package 10 of the present invention are illustrated. Includedwithin silicon microphone package 10 is a transducer 12, e.g. a siliconcondenser microphone as disclosed in U.S. Pat. No. 5,870,482 which ishereby incorporated by reference and an amplifier 16. The package itselfincludes a substrate 14, a back volume or air cavity 18, which providesa pressure reference for the transducer 12, and a cover 20. Thesubstrate 14 may be formed of FR-4 material allowing processing incircuit board panel form, thus taking advantage of economies of scale inmanufacturing. FIG. 6 is a plan view of the substrate 14 showing theback volume 18 surrounded a plurality of terminal pads.

The back volume 18 may be formed by a number of methods, includingcontrolled depth drilling of an upper surface 19 of the substrate 14 toform a recess over which the transducer 12 is mounted (FIG. 1); drillingand routing of several individual sheets of FR-4 and laminating theindividual sheets to form the back volume 18, which may or may not haveinternal support posts (FIG. 2); or drilling completely through thesubstrate 14 and providing a sealing ring 22 on the bottom of the devicethat will seal the back volume 18 during surface mounting to a user's“board” 28 (FIGS. 3-5). In this example, the combination of thesubstrate and the user's board 28 creates the back volume 18. The backvolume 18 is covered by the transducer 12 (e.g., a MEMS device) whichmay be “bumpbonded” and mounted face down. The boundary is sealed suchthat the back volume 18 is operably “air-tight.”

The cover 20 is attached for protection and processability. The cover 20contains an aperture 24 which may contain a sintered metal insert 26 toprevent water, particles and/or light from entering the package anddamaging the internal components inside; i.e. semiconductor chips. Theaperture 24 is adapted for allowing sound waves to reach the transducer12. The sintered metal insert 26 will also have certain acousticproperties, e.g. acoustic damping or resistance. The sintered metalinsert 26 may therefore be selected such that its acoustic propertiesenhance the functional capability of the transducer 12 and/or theoverall performance of the silicon microphone 10.

Referring to FIGS. 4 and 5 the final form of the product is a siliconcondenser microphone package 10 which would most likely be attached toan end user's PCB 28 via a solder reflow process. FIG. 5 illustrates amethod of enlarging the back volume 18 by including a chamber 32 withinthe end user's circuit board 28.

Another embodiment of a silicon condenser microphone package 40 of thepresent invention is illustrated in FIGS. 7-10. In this embodiment, ahousing 42 is formed from layers of materials, such as those used inproviding circuit boards. Accordingly, the housing 42 generallycomprises alternating layers of conductive and non-conductive materials44, 46. The non-conductive layers 46 are typically FR-4 board. Theconductive layers 44 are typically copper. This multi-layer housingconstruction advantageously permits the inclusion of circuitry, powerand ground planes, solder pads, ground pads, capacitance layers andplated through holes pads within the structure of the housing itself.The conductive layers provide EMI shielding while also allowingconfiguration as capacitors and/or inductors to filter input/outputsignals and/or the input power supply.

In the embodiment illustrated, the housing 42 includes a top portion 48and a bottom portion 50 spaced by a side portion 52. The housing 42further includes an aperture or acoustic port 54 for receiving anacoustic signal and an inner chamber 56 which is adapted for housing atransducer unit 58, typically a silicon die microphone or a ball gridarray package (BGA). The top, bottom, and side portions 48, 50, 52 areelectrically connected, for example with a conductive adhesive 60. Theconductive adhesive may be provided conveniently in the form of suitablyconfigured sheets of dry adhesive disposed between the top, bottom andside portions 48, 50 and 52. The sheet of dry adhesive may be activatedby pressure, heat or other suitable means after the portions are broughttogether during assembly. Each portion may comprise alternatingconductive and non-conductive layers of 44, 46.

The chamber 56 may include an inner lining 61. The inner lining 61 isprimarily formed by conductive material. It should be understood thatthe inner lining may include portions of non-conductive material, as theconductive material may not fully cover the non-conductive material. Theinner lining 61 protects the transducer 58 against electromagneticinterference and the like, much like a faraday cage. The inner lining 61may also be provided by suitable electrically coupling together of thevarious conductive layers within the top, bottom and side portions 48,50 and 52 of the housing.

In the various embodiments illustrated in FIGS. 7-10 and 23-26, theportions of the housing 42 that include the aperture or acoustic port 54further include a layer of material that forms an environmental barrier62 over or within the aperture 54. This environmental barrier 62 istypically a polymeric material formed to a film, such as apolytetrafluoroethylene (PTFE) or a sintered metal. The environmentalbarrier 62 is supplied for protecting the chamber 56 of the housing 42,and, consequently, the transducer unit 58 within the housing 42, fromenvironmental elements such as sunlight, moisture, oil, dirt, and/ordust. The environmental barrier 62 will also have inherent acousticproperties, e.g. acoustic damping/resistance. Therefore theenvironmental barrier 62 is chosen such that its acoustic propertiescooperate with the transducer unit 58 to enhance the performance of themicrophone. This is particularly true in connection with the embodimentsillustrated in FIGS. 24 and 25, which may be configured to operate asdirectional microphones.

The environmental barrier layer 62 is generally sealed between layers ofthe portion, top 48 or bottom 50 in which the acoustic port 54 isformed. For example, the environmental barrier may be secured betweenlayers of conductive material 44 thereby permitting the layers ofconductive material 44 to act as a capacitor (with electrodes defined bythe metal) that can be used to filter input and output signals or theinput power. The environmental barrier layer 62 may further serve as adielectric protective layer when in contact with the conductive layers44 in the event that the conductive layers also contain thin filmpassive devices such as resistors and capacitors.

In addition to protecting the chamber 56 from environmental elements,the barrier layer 62 allows subsequent wet processing, board washing ofthe external portions of the housing 42, and electrical connection toground from the walls via thru hole plating. The environmental barrierlayer 62 also allows the order of manufacturing steps in the fabricationof the printed circuit board-based package to be modified. Thisadvantage can be used to accommodate different termination styles. Forexample, a double sided package can be fabricated having a pair ofapertures 54 (see FIG. 25), both including an environmental barrierlayer 62. The package would look and act the same whether it is mountedface up or face down, or the package could be mounted to providedirectional microphone characteristics. Moreover, the environmentalbarrier layer 62 may also be selected so that its acoustic propertiesenhance the directional performance of the microphone.

Referring to FIGS. 7, 8, and 11-13 the transducer unit 58 is generallynot mounted to the top portion 48 of the housing. This definition isindependent of the final mounting orientation to an end user's circuitboard. It is possible for the top portion 48 to be mounted face downdepending on the orientation of the transducer 58 as well as the choicefor the bottom portion 50. The conductive layers 44 of the top portion48 may be patterned to form circuitry, ground planes, solder pads,ground pads, capacitors and plated through hole pads. Referring to FIGS.1-13 there may be additional alternating conductive layers 44,non-conductive layers 46, and environmental protective membranes 62 asthe package requires. Alternatively, some layers may be deliberatelyexcluded as well. The first non-conductive layer 46 may be patterned soas to selectively expose certain features on the first conductive layer44.

FIG. 11 illustrates an alternative top portion 48 for a microphonepackage. In this embodiment, a connection between the layers can beformed to provide a conduit to ground. The top portion of FIG. 11includes ground planes and/or pattern circuitry 64 and the environmentalbarrier 62. The ground planes and or pattern circuitry 64 are connectedby pins 65.

FIG. 12 illustrates another embodiment of a top portion 48. In additionto the connection between layers, ground planes/pattern circuitry 64,and the environmental barrier 62, this embodiment includes conductivebumps 66 (e.g. Pb/Sn or Ni/Au) patterned on the bottom side to allowsecondary electrical contact to the transducer 58. Here, conductivecircuitry would be patterned such that electrical connection between thebumps 66 and a plated through hole termination is made.

FIG. 13 illustrates yet another embodiment of the top portion 48. Inthis embodiment, the top portion 48 does not include an aperture oracoustic port 54.

Referring to FIGS. 7, 8 and 14-18, the bottom portion 50 is thecomponent of the package to which the transducer 58 is primarilymounted. This definition is independent of the final mountingorientation to the end user's circuit board. It is possible for thebottom portion 50 to be mounted facing upwardly depending on themounting orientation of the transducer 58 as well as the choice for thetop portion 48 construction. Like the top portion 48, the conductivelayers 44 of the bottom portion 50 may be patterned to form circuitry,ground planes, solder pads, ground pads, capacitors and plated throughhole pads. As shown in FIGS. 14-18, there may be additional alternatingconductive layers 44, non-conductive layers 46, and environmentalprotective membranes 62 as the package requires. Alternatively, somelayers may be deliberately excluded as well. The first non-conductivelayer 46 may be patterned so as to selectively expose certain featureson the first conductive layer 44.

Referring to FIGS. 14 a through 14 d, the bottom portion 50 comprises alaminated, multi-layered board including layers of conductive material44 deposited on layers of non-conductive material 46. Referring to FIG.14 b, the first layer of conductive material is used to attach wirebonds or flip chip bonds. This layer includes etched portions to definelead pads, bond pads, and ground pads. The pads would have holes drilledthrough them to allow the formation of plated through-holes.

As shown in FIG. 14 c, a dry film 68 of non-conductive material coversthe conductive material. This illustration shows the exposed bondingpads as well as an exposed ground pad. The exposed ground pad would comein electrical contact with the conductive epoxy and form the connectionto ground of the side portion 52 and the base portion 50.

Referring to FIG. 14 d, ground layers can be embedded within the baseportion 50. The hatched area represents a typical ground plane 64. Theground planes do not overlap the power or output pads, but will overlapthe transducer 58.

Referring to FIG. 15, an embodiment of the bottom portion 50 isillustrated. The bottom portion 50 of this embodiment includes a soldermask layer 68 and alternating layers of conductive and non-conductivematerial 44, 46. The bottom portion further comprises solder pads 70 forelectrical connection to an end user's board.

FIGS. 16 and 17 illustrate embodiments of the bottom portion 50 withenlarged back volumes 18. These embodiments illustrate formation of theback volume 18 using the conductive/non-conductive layering.

FIG. 18 shows yet another embodiment of the bottom portion 50. In thisembodiment, the back portion 50 includes the acoustic port 54 and theenvironmental barrier 62.

Referring to FIGS. 7-10 and 19-22, the side portion 52 is the componentof the package that joins the bottom portion 50 and the top portion 48.The side portion 52 may include a single layer of a non-conductivematerial 46 sandwiched between two layers of conductive material 44. Theside portion 52 forms the internal height of the chamber 56 that housesthe transducer 58. The side portion 52 is generally formed by one ormore layers of circuit board material, each having a routed window 72(see FIG. 19).

Referring to FIGS. 19-22, the side portion 52 includes inner sidewalls74. The inner sidewalls 74 are generally plated with a conductivematerial, typically copper, as shown in FIGS. 20 and 21. The sidewalls74 are formed by the outer perimeter of the routed window 72 andcoated/metallized with a conductive material.

Alternatively, the sidewalls 74 may be formed by may alternating layersof non-conductive material 46 and conductive material 44, each having arouted window 72 (see FIG. 19). In this case, the outer perimeter of thewindow 72 may not require coverage with a conductive material becausethe layers of conductive material 44 would provide effective shielding.

FIGS. 23-26 illustrate various embodiments of the microphone package 40.These embodiments utilize top, bottom, and side portions 48, 50, and 52which are described above. It is contemplated that each of the top,bottom, and side portion 48, 50, 52 embodiments described above can beutilized in any combination without departing from the inventiondisclosed and described herein.

In FIG. 23, connection to an end user's board is made through the bottomportion 50. The package mounting orientation is bottom portion 50 down.Connection from the transducer 58 to the plated through holes is be madeby wire bonding. The transducer back volume 18 is formed by the backhole (mounted down) of the silicon microphone only. Bond pads, wirebonds and traces to the terminals are not shown. A person of ordinaryskilled in the art of PCB design will understand that the traces resideon the first conductor layer 44. The wire bonds from the transducer 58are be connected to exposed pads. The pads are connected to the solderpads via plated through holes and traces on the surface.

In FIG. 24, connection to the end user's board is also made through thebottom portion 50. Again, the package mounting orientation is bottomportion 50. Connection from the transducer 58 to the plated throughholes are made by wire bonding. The back volume is formed by acombination of the back hole of the transducer 58 (mounted down) and thebottom portion 50.

In FIG. 25, connection to the end user's board is also made through thebottom portion 50. Again, the package mounting orientation is bottomportion 50. Connection from the transducer 58 to the plated throughholes are made by wire bonding. With acoustic ports 54 on both sides ofthe package, there is no back volume. This method is suitable to adirectional microphone.

In FIG. 26, connection to the end user's board is made through the topportion 48 or the bottom portion 53. The package mounting orientation iseither top portion 48 down or bottom portion 50 down. Connection fromthe transducer 58 to the plated through holes is made by flip chippingor wire bonding and trace routing. The back volume 18 is formed by usingthe air cavity created by laminating the bottom portion 50 and the topportion 48 together. Some portion of the package fabrication isperformed after the transducer 58 has been attached. In particular, thethrough hole formation, plating, and solder pad definition would be doneafter the transducer 58 is attached. The protective membrane 62 ishydrophobic and prevents corrosive plating chemistry from entering thechamber 56.

Referring to FIGS. 27-29, the portion to which the transducer unit 58 ismounted may include a retaining ring 84. The retaining ring 84 preventswicking of an epoxy 86 into the transducer 58 and from flowing into theacoustic port or aperture 54. Accordingly, the shape of the retainingring 84 will typically match the shape of the transducer 58 foot print.The retaining ring 84 comprises a conductive material (e.g., 3 mil.thick copper) imaged on a non-conductive layer material.

Referring to FIG. 27, the retaining ring 84 is imaged onto anonconductive layer. An epoxy is applied outside the perimeter of theretaining ring 84, and the transducer 58 is added so that it overlapsthe epoxy 86 and the retaining ring 84. This reduces epoxy 86 wicking upthe sides of the transducer's 58 etched port (in the case of a silicondie microphone).

Alternatively, referring to FIG. 28, the retaining ring 84 can belocated so that the transducer 58 does not contact the retaining ring84. In this embodiment, the retaining ring 84 is slightly smaller thanthe foot print of the transducer 58 so that the epoxy 86 has arestricted path and is, thus, less likely to wick. In FIG. 29, theretaining ring 84 is fabricated so that it contacts the etched port ofthe transducer 58. The following tables provide an illustrative exampleof a typical circuit board processing technique for fabrication of thehousing of this embodiment.

TABLE 1 Materials Material Type Component Note 1 0.5/0.5 oz. DST BottomPortion Cu 5 core FR-4 (Conductive Layers Non- Conductive Layer 1) 20.5/0.5 oz. DST Bottom Portion (Conductive Cu 5 core FR-4 Layers 3 and4; Non- Conductive Layer 2) 3 106 pre-preg For Laminating Material 1 andMaterial 2 4 0.5/0.5 oz. DST Side Portion Metallized Cu 40 Core FR-4Afterward 5 Bare/0.5 oz. Cu 2 Top Portion (Each Piece core FR-4 (2Includes 1 Conductive and 1 pieces) Non-Conductive Layer) 6 ExpandedPTFE Environmental Barrier

TABLE 2 Processing of Materials (Base Portion Material 1) Step TypeDescription Note 1 Dry Film Conductive Layers 2 Expose Mask Material 1(Upper Forms Ground Conductive Layer) Plane on Lower Conductive Layer 3Develop 4 Etch Cu No Etching on Upper Conductive Layer 5 Strip Dry Film

TABLE 3 Processing of Materials (Bottom Portion Material 2) Step TypeDescription Note 1 Dry Film Conductive Layers 2 Expose Mask Material 2(Upper Forms Ground Conductive Layer) Plane on Upper Conductive Layer 3Develop 4 Etch Cu No Etching on Upper Conductive Layer 5 Strip Dry Film

TABLE 4 Processing of Materials 1, 2, and 3 (Form Bottom Portion) StepType Description Note 1 Laminate Materials 1 and 2 Laminated UsingMaterial 3 2 Drill Thru Holes Drill Bit = 0.025 in. 3 Direct Plates ThruHoles Metallization/Flash Copper 4 Dry Film (L1 and L4) 5 Expose MaskLaminated Forms Traces and Materials 1 and 2 Solder Pads (Upper andLower Conductive Layers) 6 Develop 7 Electrolytic Cu 1.0 mil 8Electrolytic Sn As Required 9 Strip Dry Film 10 Etch Cu 11 Etch Cu 12Insert Finishing NG Option (See NG Option for Proof Option Here TableBelow) of Principle 13 Dry Film (cover 2.5 mil Minimum Thickness lay) onUpper on Upper Conductive Conductive Layer Layer Only 14 Expose MaskLaminated This mask defines an Materials 1 and 2 area on the upper(upper and lower) conductive layer that will receive a dry film soldermask (cover lay). The bottom layer will not have dry film applied to it.The plated through holes will be bridged over by the coating on the top.15 Develop 16 Cure Full Cure 17 Route Panels Route Bit = As Forms 4″ ×4″ pieces. Required Conforms to finished dims

Table 5 describes the formation of the side portion 52. This processinvolves routing a matrix of openings in FR-4 board. However, punchingis thought to be the cost effective method for manufacturing. Thepunching may done by punching through the entire core, or,alternatively, punching several layers of no-flow pre-preg and thin corec-stage which are then laminated to form the wall of proper thickness.

After routing the matrix, the board will have to be electroless or DMplated. Finally, the boards will have to be routed to match the bottomportion. This step can be done first or last. It may make the piece moreworkable to perform the final routing as a first step.

TABLE 5 Processing of Material 4 (Side Portion) Step Type DescriptionNote 1 Route/Punch Route Bit = 0.031 in. Forms Side Portion Matrix ofOpenings 2 Direct 0.25 mil minimum Forms Sidewalls Metallization/ onSide Portion Flash Cu 3 Route Panels

Table 6 describes the processing of the top portion. The formation ofthe top portion 48 involves imaging a dry film cover lay or liquidsolder mask on the bottom (i.e. conductive layer forming the innerlayer. The exposed layer of the top portion 48 will not have a coppercoating. It can be processed this way through etching or purchased thisway as a one sided laminate.

A matrix of holes is drilled into the lid board. Drilling may occurafter the imaging step. If so, then a suitable solder mask must bechosen that can survive the drilling process.

TABLE 6 Processing of Top Portion Step Type Description Note 1 Dry FilmConductive Layer 2 Expose Mask Bare Layer Form Conduction Ring 3 Develop4 Cure 5 Drill Matrix of Drill Bit 0.025 in. Acoustic Ports Holes 6Laminate PTFE (Environmental Forms Top Portion Barrier) Between 2 Piecesof Material 5

TABLE 7 Processing of Laminated Materials 1 and 2 with Material 4 StepType Description Note 1 Screen Conductive Adhesive on Material 4 2Laminate Bottom Portion with Side Forms Bottom Portion Portion with SidePortion (spacer) 3 Add Transducer Silicon Die Microphone Assembly andIntegrated Circuit

TABLE 8 Processing of Laminated Materials 1, 2, and 4 with Material 5Step Type Description Note 1 Screen Conductive Adhesive on Top Portion 2Laminate Bottom Portion and Side Forms Housing Portion with Top Portion3 Dice

TABLE 9 Finishing Option NG (Nickel/Gold) Step Type Description Note 1Immersion Ni (40-50 μ-in) 2 Immersion Au (25-30 μ-in)

TABLE 10 Finishing Option NGT (Nickel/Gold/Tin) Step Type 1 Mask L2(using thick dry film or high tack dicing tape) 2 Immersion Ni (40-50μ-in) 3 Immersion Au (25-30 μ-in) 4 Remove Mask on L2 5 Mask L1 (usingthick dry film or high tack dicing tape) bridge over cavity created bywall 6 Immersion Sn (100-250 μ-in) 7 Remove Mask on L1

TABLE 11 Finishing Option ST (Silver/Tin) Step Type 1 Mask L2 (usingthick dry film or high tack dicing tape) 2 Immersion Ag (40-50 μ-in) 3Remove Mask on L2 4 Mask L1 (using thick dry film or high tack dicingtape) bridge over cavity created by wall 5 Immersion Sn (100-250 μ-in) 6Remove Mask on L1

FIG. 30 is a plan view illustrating a panel 90 for forming a pluralityof microphone packages 92. The microphone packages 92 are distributed onthe panel 90 in a 14×24 array, or 336 microphone packages total. Feweror more microphone packages may be disposed on the panel 90, or onsmaller or larger panels. As described herein in connection with thevarious embodiments of the invention, the microphone packages include anumber of layers, such as top, bottom and side portions of the housing,environmental barriers, adhesive layers for joining the portions, andthe like. To assure alignment of the portions as they are broughttogether, each portion may be formed to include a plurality of alignmentapertures 94. To simultaneously manufacture several hundred or evenseveral thousand microphones, a bottom layer, such as described herein,is provided. A transducer, amplifier and components are secured atappropriate locations on the bottom layer corresponding to each of themicrophones to be manufactured. An adhesive layer, such as a sheet ofdry adhesive is positioned over the bottom layer, and a sidewall portionlayer is positioned over the adhesive layer. An additional dry adhesivelayer is positioned, followed by an environmental barrier layer, anotherdry adhesive layer and the top layer. The dry adhesive layers areactivated, such as by the application of heat and/or pressure. The panelis then separated into individual microphone assemblies using knownpanel cutting and separating techniques.

The microphone, microphone package and method of assembly hereindescribed further allow the manufacture of multiple microphone assembly,such as microphone pairs. In the simplest form, during separation twomicrophones may be left joined together, such as the microphone pair 96shown in FIG. 31. Each microphone 98 and 100 of the microphone pair 96is thus a separate, individually operable microphone in a single packagesharing a common sidewall 102. Alternatively, as described herein,conductive traces may be formed in the various layers of either the topor bottom portion thus allowing multiple microphones to be electricallycoupled.

While specific embodiments have been illustrated and described, numerousmodifications come to mind without significantly departing from thespirit of the invention, and the scope of protection is only limited bythe scope of the accompanying Claims.

What is claimed is:
 1. A solder reflow surface mountmicro-electro-mechanical system (MEMS) microphone, the microphonecomprising: a lid having top and bottom surfaces and comprising at leastone conductive layer, at least one non-conductive layer, and an acousticport, wherein at least one the conductive layer comprises the bottomsurface of the lid, and wherein the bottom surface has an attachmentregion and an interior region, the attachment region positioned betweenthe interior region and the edges of the lid, and completely boundingthe interior region; a sidewall spacer having top and bottom surfacesand comprising at least two conductive layers with a center layer ofnon-conductive material having predefined thickness disposed between thetwo conductive layers, wherein one conductive layer comprises the topsurface of the sidewall spacer and the other conductive layer comprisesthe bottom surface of the sidewall spacer, and wherein the sidewallspacer further comprises an opening having walls covered with conductivematerial, and the opening walls extend through the center layer to thetop surface and the bottom surface; a substrate comprising: a base layercomprised of at least one layer of non-conductive material, wherein thebase layer has a planar top surface and a planar bottom surface, the topsurface having an interior region and an attachment region, theattachment region disposed between the interior region and the edges ofthe base layer, and completely bounding the interior region; a firstplurality of metal pads disposed on the top surface of the base layer,wherein at least one pad of the first plurality of metal pads is locatedin the attachment region of the top surface of the base layer; a secondplurality of metal pads disposed on the bottom surface of the baselayer, the second plurality of metal pads arranged to be within theedges of the base layer; and one or more electrical pathways disposedcompletely within the base layer, wherein the pathways electricallycouple one or more of the first plurality of metal pads on the topsurface of the base layer to one or more of the second plurality ofmetal pads on the bottom surface of the base layer, and wherein the atleast one metal pad located in the attachment region of the top surfaceof the base layer is electrically coupled to one or more of the secondplurality of metal pads; a MEMS microphone die mounted on the topsurface of the base layer, and electrically coupled to at least one ofthe first plurality of metal pads on the top surface of the base layer;wherein the substrate, the sidewall spacer and the lid cooperate witheach other to form a housing, wherein the edges of the substrate, thesidewall spacer and the lid create side surfaces substantiallyperpendicular to the bottom surface of the substrate, and wherein thehousing has an internal acoustic chamber for the MEMS microphone die;wherein the bottom surface of the sidewall spacer is coupled to theattachment region of the top surface of the substrate such that theopening of the sidewall spacer and the interior region of the topsurface of the substrate are aligned, and the conductive material on theopening walls of the sidewall spacer is electrically coupled to the atleast one metal pad located in the attachment region of the substrate;wherein the top surface of the sidewall spacer is coupled to theattachment region of the bottom surface of the lid such that the openingof the sidewall spacer and the interior region of the bottom surface ofthe lid are aligned, and the conductive layer of the lid is electricallycoupled to the conductive material on the opening walls of the sidewallspacer; and wherein the interior region of the top surface of thesubstrate, the opening walls of the sidewall spacer, and the interiorregion of the bottom surface of the lid, when attached, define theinternal acoustic chamber for the MEMS microphone die.
 2. A surfacemount MEMS microphone according to claim 1, further comprising at leastone passive electrical element electrically coupled between one of thefirst plurality of metal pads and one of the second plurality of metalpads.
 3. A surface mount MEMS microphone according to claim 2, whereinthe at least one passive electrical element is disposed within the baselayer of the substrate.
 4. A surface mount MEMS microphone according toclaim 2, wherein the at least one passive electrical element is disposedwithin the base layer of the substrate and comprises a dielectric orresistive material that is different from the non-conductive material ofthe base layer.
 5. A surface mount MEMS microphone according to claim 2,wherein the at least one passive electrical element filters one or moreof an input signal, an output signal, or input power.
 6. A surface mountMEMS microphone according to claim 1, wherein the lid is attached to thesidewall spacer with a first conductive material, and the substrate isattached to the sidewall spacer with a second conductive material.
 7. Asurface mount MEMS microphone according to claim 1, wherein the housingprotects the MEMS microphone die from at least one of light,electromagnetic interference, and physical damage.
 8. A surface mountMEMS microphone according to claim 1, wherein the housing furthercomprises a material that substantially blocks environmentalcontaminants from entering the acoustic chamber through the acousticport.
 9. A surface mount MEMS microphone according to claim 1, whereinthe lid further comprises a material layer that that substantiallyblocks environmental contaminants from entering the acoustic chamberthrough the acoustic port.
 10. A surface mount MEMS microphone accordingto claim 1, wherein the acoustic port is disposed in a position offsetfrom the lid centerpoint.
 11. A surface mount MEMS microphone accordingto claim 1, wherein sidewall spacer comprises multiple layers ofconductive and non-conductive material, and the conductive material onthe opening walls electrically couples the conductive layers to eachother.
 12. A surface mount MEMS microphone according to claim 1, whereinthe first and second pluralities of metal pads on the base layer of thesubstrate are plated with a metal that is different from the metal usedfor the first and second pluralities of metal pads.
 13. A surface mountMEMS microphone according to claim 1, wherein the base layer of thesubstrate further comprises at least one additional non-conductive layerand at least one additional conductive layer.
 14. A surface mount MEMSmicrophone according to claim 1, wherein the base layer of the substratefurther comprises a recess disposed therein, and MEMS microphone die ispositioned over the recess.
 15. A surface mount MEMS microphoneaccording to claim 1, wherein the base layer of the substrate furthercomprises an internal cavity with an aperture in the top surface of thebase layer, and the MEMS microphone die is positioned over the aperturein the top surface of the base layer.
 16. A surface mount MEMSmicrophone according to claim 1, wherein the acoustic port disposed inthe lid is a first acoustic port, and the base layer of the substratefurther comprises a second acoustic port, and wherein the MEMSmicrophone die is positioned over the second acoustic port in the baselayer.
 17. A surface mount MEMS microphone according to claim 16,wherein the base layer of the substrate further comprises a materiallayer that that substantially blocks environmental contaminants fromreaching the MEMS microphone die through the second acoustic port in thebase layer.
 18. A surface mount MEMS microphone according to claim 1,wherein electrical continuity is present between the conductive layer inthe lid, the conductive material on the opening walls of the sidewallspacer, and at least one of the second plurality of metal pads.
 19. Asurface mount MEMS microphone according to claim 1, wherein the at leastone non-conductive layer of the lid, the center layer of non-conductivematerial of the sidewall spacer, and the non-conductive material of thebase layer each have a substantially similar predetermined coefficientof thermal expansion.
 20. A solder reflow surface mountmicro-electro-mechanical system (MEMS) microphone, the microphonecomprising: a top portion having upper and lower surfaces and comprisingat least one metal layer, at least one printed circuit board materiallayer, and an acoustic port, wherein the at least one metal layercomprises the lower surface of the top portion, and wherein the lowersurface has a coupling area and an inner area, the coupling area beingarranged between the inner area and the edges of the top portion, andcompletely surrounding the inner area; a spacer portion having upper andlower surfaces and comprising at least two metal layers with at leastone printed circuit board material layer of predefined thicknessdisposed between the two metal layers, wherein one metal layer comprisesthe upper surface of the spacer portion and the other metal layercomprises the lower surface of the spacer portion, and wherein thespacer portion further comprises a window having walls covered with ametal layer, and the window walls extend through the printed circuitboard material layer to the upper surface and the lower surface; abottom portion comprising: a base layer comprised of at least one layerof printed circuit board material, wherein the base layer has asubstantially flat upper surface and a substantially flat lower surface,the upper surface having an inner area and a coupling area, the couplingarea located between the inner area and the edges of the base layer, andcompletely surrounding the inner area; a plurality of metal pads locatedon the upper surface of the base layer, wherein at least one pad of theplurality of metal pads is positioned in the coupling area of the uppersurface of the base layer; a plurality of solder pads located on thelower surface of the base layer, the plurality of solder pads arrangedto be within the edges of the base layer; one or more electricalconnections passing through the base layer, wherein the connectionselectrically couple one or more of the plurality of metal pads on theupper surface of the base layer to one or more of the plurality ofsolder pads on the lower surface of the base layer, and wherein the atleast one metal pad positioned in the coupling area of the upper surfaceof the base layer is electrically coupled to one or more of theplurality of solder pads; and at least one passive electrical elementelectrically coupled between one of the plurality of metal pads and oneof the plurality of solder pads; a MEMS microphone die physicallycoupled to the upper surface of the base layer, and electrically coupledto at least one of the plurality of metal pads on the upper surface ofthe base layer; wherein the bottom portion, the spacer portion and thetop portion cooperate with each other to form a housing having asubstantially rectangular shape with an internal acoustic chamber forthe MEMS microphone die, and that protects the MEMS microphone die fromat least one of light, electromagnetic interference, and physicaldamage; wherein a conductive material physically couples the lowersurface of the spacer portion to the coupling area of the upper surfaceof the bottom portion such that the window of the spacer portion and theinner area of the upper surface of the bottom portion are aligned, andthe metal layer on the window walls of the spacer portion iselectrically coupled to the at least one metal pad positioned in thecoupling area of the bottom portion; wherein a conductive materialphysically couples the upper surface of the spacer portion to thecoupling area of the lower surface of the top portion such that thewindow of the spacer portion and the inner area of the lower surface ofthe top portion are aligned, and the metal layer of the top portion iselectrically coupled to the metal layer on the window walls of thespacer portion; wherein electrical continuity is present between the atleast one metal layer in the top portion, the metal layer on the windowwalls of the spacer portion, and at least one of the plurality of solderpads; and wherein the inner area of the upper surface of the bottomportion, the window walls of the spacer portion, and the inner area ofthe lower surface of the top portion, when attached, define the internalacoustic chamber that acoustically couples the MEMS microphone die tothe acoustic port.
 21. A surface mount MEMS microphone according toclaim 20, wherein the housing further comprises a material thatsubstantially blocks environmental contaminants from entering theacoustic chamber through the acoustic port.
 22. A surface mount MEMSmicrophone according to claim 20, wherein the acoustic port is disposedin a position offset from the centerpoint of the top portion.
 23. Asurface mount MEMS microphone according to claim 20, wherein the bottomportion further comprises a cavity with an opening in the upper surfaceof the base layer, and the MEMS microphone die is positioned over theopening in the upper surface of the base layer such that the MEMSmicrophone die is acoustically coupled to the cavity.
 24. A surfacemount MEMS microphone according to claim 20, wherein the base layer ofthe bottom portion further comprises an acoustic port, and wherein theMEMS microphone die is positioned over the acoustic port in the bottomportion.
 25. A surface mount MEMS microphone according to claim 20,wherein the at least one passive electrical element is disposed withinthe base layer of the bottom portion and comprises a dielectric orresistive material that is different from the printed circuit boardmaterial of the base layer.
 26. A surface mount MEMS microphoneaccording to claim 25, wherein the at least one passive electricalelement filters one or more of an input signal, an output signal, orinput power.
 27. A surface mount MEMS microphone according to claim 20,wherein the printed circuit board layer of the spacer portion furthercomprises additional layers of printed circuit board materialalternating with additional metal layers, and the conductive material onthe window walls electrically couples the additional metal layers toeach other.
 28. A surface mount MEMS microphone according to claim 20,wherein the base layer of the bottom portion further comprises at leastone additional non-conductive layer and at least one additionalconductive layer.
 29. A surface mount MEMS microphone according to claim20, wherein the first enclosure element further comprises additionalmetal layers alternating with the FR-4 printed circuit board materiallayers, and the metal layer of the interior open volume wallselectrically couples the additional metal layers to each other.
 30. Asolder reflow surface mount micro-electro-mechanical system (MEMS)microphone, the microphone comprising: a base substrate comprising: acore layer comprised of at least one layer of FR-4 printed circuit boardmaterial, wherein the core layer has a substantially flat top surfaceand a substantially flat bottom surface, the top surface having a diemount region and an attachment region, the attachment region positionedbetween the die mount region and the edges of the core layer, andcompletely surrounding the die mount region; a plurality of metal padslocated on the top surface of the core layer, wherein at least one padof the plurality of metal pads is located in the attachment region ofthe top surface of the core layer; a plurality of solder pads located onthe bottom surface of the core layer, the plurality of solder padsarranged to be within the edges of the core layer; a plurality ofelectrical connections passing through the core layer that electricallycouple one or more of the plurality of metal pads on the top surface ofthe core layer to one or more of the plurality of solder pads on thebottom surface of the core layer, and wherein the at least one metal padlocated in the attachment region of the top surface of the core layer iselectrically coupled to one or more of the plurality of solder pads; anda pressure-equalizing MEMS microphone die having an internal acousticchannel mounted in the die mount region of the core layer, andelectrically coupled to one or more of the metal pads on the top surfaceof the core layer; an enclosure comprising: a first enclosure elementhaving substantially flat top and bottom surfaces and comprising atleast two metal layers with multiple FR-4 printed circuit board materiallayers of predefined thickness disposed between the two metal layers,wherein one metal layer comprises the top surface of the first enclosureelement and the other metal layer comprises the bottom surface of thefirst enclosure element; a second enclosure element having substantiallyflat top and bottom surfaces and comprising at least one metal layer, atleast one FR-4 printed circuit board material layer, and an acousticport that is disposed in an offset position from the centerpoint of thesecond enclosure element, wherein the metal layer comprises the bottomsurface of the second enclosure element, and wherein the bottom surfacehas an attachment region and an inner region, the attachment regionbeing arranged between the attachment region and the edges of the secondenclosure element, and completely surrounding the attachment region;wherein a conductive material physically couples the top surface of thefirst enclosure element to the attachment region of the bottom surfaceof the second enclosure element; wherein the first enclosure elementcomprises an interior open volume with walls, thereby exposing the innerregion of the bottom surface of the second enclosure element; andwherein the interior open volume walls have a metal layer that iselectrically connected to the bottom surface metal layer of the secondenclosure element; the base substrate and the enclosure being joinedtogether to form a housing that has an internal acoustic chamber for theMEMS microphone die, and that protects the MEMS microphone die from atleast one of light, electromagnetic interference, and physical damage,wherein a conductive material physically couples the bottom surfacemetal layer of the first enclosure element to the attachment region ofthe base substrate, and wherein the interior open volume of the firstenclosure element is aligned with the die mount region of the basesubstrate and the metal pad positioned in the attachment region iselectrically coupled to the metal layer of the interior open volumewalls in the first enclosure element; wherein the interior region of thebottom surface of the second enclosure element, the interior open volumewalls of the first enclosure element, and the die mount region of thebase substrate define the internal acoustic chamber that is a frontvolume for the MEMS microphone die, and acoustically couples theacoustic port to the MEMS microphone die; wherein electrical continuityexists between the metal layer of the second enclosure element, themetal-covered interior open volume walls of the enclosure element, andone or more of the plurality of solder pads on the base substrate; andwherein the length of the base substrate and the length of the enclosureare substantially equal, and the width of the base substrate and thewidth of the enclosure are substantially equal.
 31. A surface mount MEMSmicrophone according to claim 30, further comprising at least onepassive electrical element electrically coupled between one of theplurality of metal pads and one of the plurality of solder pads, anddisposed within the core layer of the base substrate.
 32. A surfacemount MEMS microphone according to claim 31, wherein the at least onepassive electrical element is disposed within the core layer of the basesubstrate and comprises a dielectric or resistive material that isdifferent from the FR-4 printed circuit board material of the corelayer.
 33. A surface mount MEMS microphone according to claim 32,wherein the at least one passive electrical element filters one or moreof an input signal, an output signal, or input power.
 34. A surfacemount MEMS microphone according to claim 30, wherein the housing furthercomprises a material that substantially blocks environmentalcontaminants from entering the acoustic chamber through the acousticport.
 35. A surface mount MEMS microphone according to claim 30, whereinthe core layer of the base substrate further comprises an internalcavity with an aperture in the top surface of the core layer, and theinternal acoustic channel of the MEMS microphone die is positioned overand acoustically coupled to the aperture in the top surface of the corelayer.
 36. A solder reflow surface mount micro-electro-mechanical system(MEMS) microphone, the microphone comprising: a pressure-equalizing MEMSmicrophone die having an internal acoustic channel; a housing for theMEMS microphone die comprising: a first housing element havingsubstantially flat top and bottom surfaces and comprising at least atleast one metal layer, at least one printed circuit board materiallayer, and an acoustic port, wherein the at least one metal layercomprises the bottom surface of the first housing element, wherein thebottom surface has an attachment region and an interior region, theattachment region located between the interior region and the edges ofthe first housing element and completely surrounding the interiorregion, and wherein the acoustic port is disposed in a position offsetfrom the centerpoint of the first housing element; a second housingelement having substantially flat top and bottom surfaces and comprisingat least first and second metal layers with multiple printed circuitboard material layers of predefined thickness disposed between the firstand second metal layers, wherein the first metal layer comprises the topsurface of the second housing element and the second metal layercomprises the bottom surface of the second housing element, and whereinthe second housing element further comprises an aperture havingmetal-covered walls, and the aperture walls extend through the printedcircuit board material layer to the top and bottom surfaces of thesecond housing element; a third housing element comprising: a core layercomprised of at least one layer of printed circuit board material,wherein the core layer has a substantially flat top surface and asubstantially flat bottom surface, wherein the top surface has aninterior region and an attachment region, the attachment region beingarranged between the interior region and the edges of the core layer,and the attachment region completely surrounds the interior region; aplurality of metal pads disposed on the top surface of the core layer,wherein at least one pad of the plurality of metal pads is positioned inthe attachment region of the top surface of the core layer; a pluralityof solder pads disposed on the bottom surface of the core layer, theplurality of solder pads arranged to be within the edges of the corelayer; and one or more electrical vias located inside the core layer,wherein the vias electrically couple one or more of the plurality ofmetal pads on the top surface of the core layer to one or more of theplurality of solder pads on the bottom surface of the core layer, andwherein a via electrically couples the at least one metal pad positionedin the attachment region of the top surface of the core layer to one ormore of the plurality of solder pads; wherein the MEMS microphone die isphysically coupled to the top surface of the core layer, andelectrically coupled to at least one of the plurality of metal pads onthe top surface of the core layer; wherein the first, second, and thirdhousing elements cooperate with each other to form a housing, whereinthe edges of the first, second, and third housing elements create sidesurfaces substantially perpendicular to the bottom surface of the thirdhousing element, wherein the housing has an internal acoustic chamberfor the MEMS microphone die, and wherein the housing protects the MEMSmicrophone die from at least one of light, electromagnetic interference,and physical damage; wherein a conductive material physically couplesthe attachment region of the bottom surface of the first housing elementto the top surface of the second housing element to such that theinterior region of the bottom surface of the first housing element andthe aperture of the second housing element are aligned, and the metallayer of the first housing element is electrically coupled to themetal-covered aperture walls of the second housing element; wherein aconductive material physically couples the bottom surface of the secondhousing element to the attachment region of the top surface of the thirdhousing element such that the aperture of the second housing element andthe interior region of the top surface of the third housing element arealigned, and the metal-covered aperture walls of the second housingelement are electrically coupled to the at least one metal padpositioned in the attachment region of the third housing element;wherein the interior region of the bottom surface of the first housingelement, the aperture walls of the second housing element, and theinterior region of the top surface of the third housing element, whenattached, define the internal acoustic chamber that is a front volumefor the MEMS microphone die, and acoustically couples the acoustic portto the MEMS microphone die; and wherein electrical continuity existsbetween the metal layer of the first housing element, the metal-coveredaperture walls of the second housing element, and one or more of theplurality of solder pads on the third housing element.
 37. A surfacemount MEMS microphone according to claim 36, further comprising at leastone passive electrical element electrically coupled between one of theplurality of metal pads and one of the plurality of solder pads.
 38. Asurface mount MEMS microphone according to claim 37, wherein the atleast one passive electrical element is disposed within the core layerof the third housing element and comprises a dielectric or resistivematerial that is different from the printed circuit board material ofthe core layer.
 39. A surface mount MEMS microphone according to claim38, wherein the at least one passive electrical element filters one ormore of an input signal, an output signal, or input power.
 40. A surfacemount MEMS microphone according to claim 37, wherein the second housingelement further comprises additional metal layers interposed between themultiple layers of printed circuit board material, and the metal-coveredwalls of the aperture electrically couples the additional metal layersto each other.
 41. A surface mount MEMS microphone according to claim36, wherein the housing further comprises a material that substantiallyblocks environmental contaminants from entering the acoustic chamberthrough the acoustic port.
 42. A surface mount MEMS microphone accordingto claim 36, wherein the third housing element further comprises acavity with an opening in the top surface of the core layer of the thirdhousing element, and the MEMS microphone die is positioned over theopening in the top surface of the core layer such that the internalacoustic channel of the MEMS microphone die is acoustically coupled tothe cavity.